This invention relates to phenone ketals having a special structure and to their use as perfumes.
Judging by demand, many natural perfumes are available in totally inadequate quantities. For example, 5,000 kg of rose blossoms are required to obtain 1 kg of rose oil. The consequences are extremely limited annual world production and a high price. Accordingly, it is clear that there is a constant need in the perfume industry for new perfumes with interesting fragrance notes in order to extend the range of naturally available perfumes, to make the necessary adaptations to changing fashion trends and to be able to meet the steadily increasing demand for odor enhancers for products of everyday use, such as cosmetics and cleaners.
Accordingly, it is clear that there is a constant need in the perfume industry for new perfumes with interesting fragrance notes in order to extend the range of naturally available perfumes, to make the necessary adaptations to changing fashion trends and to be able to meet the steadily increasing demand for odor enhancers for products of everyday use, such as cosmetics and cleaners.
In addition, there is generally a constant need for synthetic perfumes which can be favorably produced in a consistent quality and which have desirable olfactory properties, i.e. pleasant, near-natural and qualitatively new odor profiles of adequate intensity, and which are capable of advantageously influencing the fragrance of cosmetic and consumer products. In other words, there is a constant need for compounds which have characteristic new odor profiles coupled with high staying power, intensity of odor and emanative power.
It has now been found that special phenone ketals corresponding to formula (I) below excellently satisfy the requirements mentioned above in every respect and may advantageously be used as perfumes with differently nuanced odor notes characterized by high staying power.
In a first embodiment, the present invention relates to phenone ketals corresponding to general formula (I): 
where X and Y independently of one another represent methoxy, ethoxy, propoxy or butoxy groups and R1 is a methyl, ethyl or propyl group, R2 is hydrogen or a methyl, ethyl, isopropyl, tert.butyl or methoxy group, R3 is hydrogen or a methoxy group and R4 is hydrogen or a methyl group.
In one preferred embodiment of the invention, the phenone ketals corresponding to general (Ia): 
where R1 is a methyl or ethyl group, R2 is a methyl, tert.butyl or methoxy group, R3 is hydrogen or a methoxy group and R4 is hydrogen or a methyl group.
In another embodiment, the present invention relates to the use of phenone ketals corresponding to general formula (I) as perfumes. The compounds (Ia) are preferably used, the compound 1-(1,1-diethoxyethyl)-2,4-dimethyl benzene, i.e. the diethyl ketal of 2,4-dimethyl acetophenone, being particularly preferred.
The carbonyl compounds according to the invention are distinguished by an odor characteristic in which flowery notes reminiscent of anthranilate, ylang and tuberose are dominant. They show excellent stability in formulations used for cosmetics and consumer perfumery.
The compounds (I) are prepared by syntheses known per se in organic chemistry. Their synthesis is carried out, for example, by stirring the ketones which are dissolved in the required alcohol and which are used in excess in the presence of dehydrating agents which may be used both in catalytic quantities (0.01 to 0.2 mol-%) and in molar quantities (where molecular sieves are used), based on the ketones. Suitable dehydrating agents are, for example, sulfates, such as magnesium, sodium or potassium sulfates and hydrogen sulfates, or sulfonic acids, such as for example p-toluenesulfonic acid, pyridinium tosylate, etc. and molecular sieves (preferably with a pore diameter of ca. 4 Angstrxc3x6ms).
The ketals according to the invention can be obtained in very pure form by distilling off the excess alcohol and fractionating the crude product.
In perfume compositions, the compounds (I) enhance harmony and emanation and also persistence, the quantities used being adapted to the particular fragrance note required taking the other ingredients of the composition into account.
The fact that the carbonyl compounds (I) have flowery, anthranilate, ylang and tuberose notes was not foreseeable and, accordingly, is further confirmation of the general experience that the olfactory properties of known perfumes are not always an indication of the properties of structurally related compounds because neither the mechanism of odor perception nor the influence of chemical structure on odor perception has been adequately researched, so that it is not normally possible to predict whether a modified structure of known perfumes will in fact lead to a change in the olfactory properties and whether these changes will be positive or negatively evaluated.
By virtue of their odor profile, the compounds corresponding to formula (I) are also particularly suitable for modifying and enhancing known compositions. Their extraordinary intensity of odor is particularly emphasized, contributing quite generally towards refining the composition.
The compounds corresponding to formula (I) may be combined with many known perfume ingredients, for example other perfumes of natural, synthetic or partly synthetic origin, essential oils and plant extracts. The range of natural perfumes can encompass both high volatility and medium to low volatility components while the range of synthetic perfumes can encompass representatives of virtually all classes of compounds. The following are examples:
(a) natural products, such as tree moss absolue, basil oil, citrus oils, such as bergamot oil, mandarin oil, etc., mastix absolue, myrtle oil, palmarosa oil, patchouli oil, petitgrain oil, absinth oil, myrrh oil, olibanum oil,
(b) alcohols, such as farnesol, geraniol, linalool, nerol, phenylethyl alcohol, rhodinol, cinnamic alcohol, sandalore [3-methyl-5-(2, 2, 3-trimethylcyclopent-3-en-1-yl)-pentan-2-ol], sandela [3-isocamphyl-(5)-cyclohexanol],
(c) aldehydes, such as citral, Helional(copyright), xcex1-hexyl cinnamic aldehyde, hydroxycitronellal, Lilial(copyright) [p-tert.butyl-xcex1-methyl dihydrocinnamic aldehyde], methyl nonyl acetaldehyde,
(d) ketones, such as allyl ionone, xcex1-ionone, xcex2-ionone, isoraldein, methyl ionone,
(e) esters, such as allylphenoxyacetate, benzyl salicylate, cinnamyl propionate, citronellyl acetate, decyl acetate, dimethyl benzylcarbinyl acetate, ethyl acetoacetate, hexenyl isobutyrate, linalyl acetate, methyl dihydrojasmonate, vetiveryl acetate, cyclohexyl salicylate,
(f) lactones, such as gamma-undecalactone, 1-oxaspiro-[4.4]-nonan-2-one,
and various other components often used in perfumery, such as musk, indole, p-menthane-8-thiol-3-one, methyl eugenol, Ambroxan.
Also remarkable is the way in which the compounds (I) round off and harmonize the odor notes of a broad range of known compositions without unpleasantly dominating them. 1-(1,1-dioxyethyl)-2,4-dimethylbenzene, i.e. the diethylketal of 2,4dimethylacetophenone, is particularly emphasized in this regard.
The percentages by weight of the compounds according to the invention or mixtures thereof which can be used in perfume compositions range from 1 to 70% by weight, based on the mixture as a whole. Mixtures of the compounds (I) according to the invention and compositions of this type may be used both for perfuming cosmetic preparations, such as lotions, cremes, shampoos, soaps, emollients, powders, aerosols, toothpastes, mouthwashes, deodorants, and in alcohol-based perfumery (for example colognes, toilet waters, extracts). They may also be used for perfuming industrial products, such as detergents and cleaners, fabric softeners and textile treatment compositions. For perfuming these various products, the compositions are added in an olfactorily effective quantity, more particularly in a concentration of 0.05 to 2% by weight, based on the product as a whole. However, these values are not intended to represent particular limits because the experienced perfumer can obtain effects with lower concentrations or can create new complexes with even higher concentrations.